Method for high dynamic range image construction based on multiple images with multiple illumination intensities

Abstract

A method for increasing the dynamic light intensity range of an image by combining pixel data from multiple images collected at different levels of illumination intensity to create a single floating-point image representation of an observed scene.

What is claimed is:  
     
       1. A method for generating an image having an expanded illumination range of an observed scene, comprising: 
       obtaining a first image of said observed scene at a first illumination level;  
       obtaining one or more additional images of said observed scene, each said additional image being taken at an associated unique illumination level;  
       registering said first image and said one or more additional images;  
       identifying at least one of either a dark region or a saturated region in said first image;  
       replacing said identified dark region in said first image with information extracted from a corresponding illuminated region in said one or more additional images; and  
       replacing said identified saturated region in said first image with information extracted from a corresponding unsaturated region in said one or more additional images.  
     
     
       2. The method of  claim 1  further comprising scaling each said unique illumination level for each of said replaced regions to said first illumination level. 
     
     
       3. The method of  claim 1  wherein illumination levels within said first image are represented by floating-point values. 
     
     
       4. A method for generating an image having an expanded illumination range of an observed scene, comprising: 
       obtaining a first image of said observed scene at a first illumination level, said first image composed of a set of pixels;  
       obtaining one or more additional images of said observed scene, each of which is taken at a unique illumination level scaled to said first illumination level and composed of sets of associated pixels;  
       registering said set of pixels comprising said first image with corresponding sets of associated pixels comprising said one or more additional images;  
       identifying at least one of either a dark pixel or a saturated pixel in said set of pixels comprising said first image;  
       for each identified dark pixel, replacing said identified dark pixel with a corresponding illuminated pixel from a set of associated pixels comprising said one or more additional images;  
       for each identified saturated pixel, replacing said identified saturated pixel with a corresponding illuminated pixel from a set of associated pixels comprising said one or more additional images; and  
       applying an associated illumination scale factor to each replaced pixel in said set of pixels comprising said first image.  
     
     
       5. The method of  claim 4  for generating an image having an expanded illumination range of an observed scene wherein the step of applying an associated illumination scale factor to each replaced pixel includes calculating a floating point illumination intensity value for each replaced pixel. 
     
     
       6. A method for generating an image of an observed scene composed of a set of pixels having an expanded illumination range, comprising: 
       obtaining a plurality of images of said observed scene, each of said plurality of images obtained at a different illumination level;  
       registering each of said plurality of images; and  
       generating a composite image of said observed scene from said plurality of images, wherein each pixel within a set of pixels comprising said composite image is an illuminated pixel.  
     
     
       7. The method of  claim 6  wherein the step of generating a composite image includes: 
       for each pixel within said set of pixels comprising said composite image, selecting a corresponding illuminated pixel from one of said plurality of images;  
       establishing an illumination level for said composite image; and  
       for each pixel within said set of pixels comprising said composite image, scaling an illumination level associated with said pixel to said established illumination level.  
     
     
       8. The method of  claim 6  wherein the step of generating a composite image includes the step of scaling, with an associated illumination scale factor, an illumination intensity value of one or more pixels within said set of pixels comprising said composite image. 
     
     
       9. The method of  claim 6  wherein the step of generating a composite image includes the step of calculating a floating point illumination intensity value for one or more pixels within said set of pixels comprising said composite image. 
     
     
       10. A method for generating an image of an observed scene, comprising: 
       obtaining a first image of said observed scene, said first image having an observed illumination level;  
       altering, at least once, one or more parameters affecting said imaged illumination level of said observed scene;  
       obtaining, for each alteration of said one or more parameters, an additional image of said observed scene at an associated observed illumination level;  
       registering said first image and said one or more additional images;  
       identifying at least one of either a dark region or a saturated region in said first image;  
       replacing each said identified dark region in said first image with information extracted from a corresponding illuminated region in said one or more additional images; and  
       replacing each said identified saturated region in said first image with information extracted from a corresponding illuminated region in said one or more additional images.  
     
     
       11. The method of  claim 10  for generating an image of an observed scene wherein the step of altering, at least once, one or more parameters affecting said imaged illumination level of said observed scene includes altering the illumination of said observed scene. 
     
     
       12. The method of  claim 10  for generating an image of an observed scene wherein the step of altering, at least once, one or more parameters affecting said imaged illumination level of said observed scene includes altering a camera setting. 
     
     
       13. The method of  claim 10  for generating an image of an observed scene wherein the step of altering, at least once, one or more parameters affecting said imaged illumination level of said observed scene includes altering an illumination light source setting. 
     
     
       14. The method of  claim 10  for generating an image of an observed scene wherein the step of altering, at least once, one or more parameters affecting said imaged illumination level of said observed scene includes altering an imaging sensor setting.